Pass root ServerWindow id to FrameGenerator.

services/ui/ws/frame_generator.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "services/ui/ws/frame_generator.h"
 
 #include "base/containers/adapters.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/quads/render_pass.h"
 #include "cc/quads/render_pass_draw_quad.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/surface_draw_quad.h"
 #include "cc/surfaces/surface_id.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
 #include "services/ui/surfaces/display_compositor_frame_sink.h"
 #include "services/ui/ws/frame_generator_delegate.h"
 #include "services/ui/ws/server_window.h"
 #include "services/ui/ws/server_window_compositor_frame_sink.h"
 #include "services/ui/ws/server_window_compositor_frame_sink_manager.h"
 
 namespace ui {
 
 namespace ws {
 
 FrameGenerator::FrameGenerator(
     FrameGeneratorDelegate* delegate,
+    WindowId root_window_id,
     scoped_refptr<DisplayCompositor> display_compositor)
     : delegate_(delegate),
       display_compositor_(display_compositor),
-      frame_sink_id_(0, display_compositor->GenerateNextClientId()),
+      frame_sink_id_(
+          WindowIdToTransportId(root_window_id),
+          static_cast<uint32_t>(mojom::CompositorFrameSinkType::DEFAULT)),

[Fady Samuel, 2016/10/24 21:53:22]

https://cs.chromium.org/chromium/src/base/numerics/safe_conversions.h?q=base:...

https://cs.chromium.org/chromium/src/content/browser/frame_host/render_widget...

[kylechar, 2016/10/25 18:15:02]

The error is actually with enum inputs to base::checked_cast. Looks like
enum/enum class returns false for std::is_arithmetic<> and a static_assert fails
when using base::checked_cast<>. It's basically this that fails:

static_assert(std::is_arithmetic<mojom::CompositorFrameSinkType>::value, "...");

       draw_timer_(false, false),
       weak_factory_(this) {
   DCHECK(delegate_);
   surface_sequence_generator_.set_frame_sink_id(frame_sink_id_);
 }
 
 FrameGenerator::~FrameGenerator() {
   ReleaseAllSurfaceReferences();
   // Invalidate WeakPtrs now to avoid callbacks back into the
   // FrameGenerator during destruction of |compositor_frame_sink_|.
@@ skipping 272 matching lines @@
     ReleaseFrameSinkReference(default_compositor_frame_sink->frame_sink_id());
   ServerWindowCompositorFrameSink* underlay_compositor_frame_sink =
       surface_manager->GetUnderlayCompositorFrameSink();
   if (underlay_compositor_frame_sink)
     ReleaseFrameSinkReference(underlay_compositor_frame_sink->frame_sink_id());
 }
 
 }  // namespace ws
 
 }  // namespace ui